An electricity consumer in Helsinki only had a total average of about three minutes of power cuts in 2013.
According to the outage statistics newly published by Finnish Energy Industries, average interruption times in electricity distribution in 2013 totalled about 4 hours per electricity user. Damage was caused by storms especially to overhead power lines in rural areas.
– The situation in Helsinki is quite different compared with the rest of the country, explains Managing Director Risto Harjanne of Helen Sähköverkko Oy. – About 98% of our distribution network is located underground, which is clearly a higher percentage than elsewhere in the country. Rapid stand-by supply connections have also been taken into account in the construction of the electricity network Helsinki, and consequently the impact of disturbances can be minimised. We have also invested in increasing the level of automation in the electricity network.
Excavation damages account for most distribution outages
The majority of power cuts in Helsinki, 20–50 per year, are caused by careless excavation resulting in damage to medium-voltage cables. Each year, faults caused by natural phenomena, such as wind, lightning or birds, occur on the 110-kV transmission lines, but these do not usually result in a power cut. Equipment failure in substations is fairly rare, but it may cause disruption to electricity supply once every five years on the average.
Helsinki’s electricity distribution system excels in international benchmarking
Helen Sähköverkko Oy came on top in an international benchmarking study (International Distribution Benchmarking Consortium) on the quality and reliability of electricity supply. The automation level of Helsinki’s distribution network was the highest in the comparison, and Helsinki is a forerunner in the utilisation of automation in distribution substations even on the international scale.